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iOSOperating system · Cisco

CVE-2015-6280

HIGH · 9.3 CVSS v2.0 Published 2015-09-28
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The SSHv2 functionality in Cisco IOS 15.2, 15.3, 15.4, and 15.5 and IOS XE 3.6E before 3.6.3E, 3.7E before 3.7.1E, 3.10S before 3.10.6S, 3.11S before 3.11.4S, 3.12S before 3.12.3S, 3.13S before 3.13.3S, and 3.14S before 3.14.1S does not properly implement RSA authentication, which allows remote attackers to obtain login access by leveraging knowledge of a username and the associated public key, aka Bug ID CSCus73013.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The SSHv2 implementation in Cisco IOS and IOS XE contains a flaw in RSA public key authentication that allows remote attackers to bypass authentication entirely. An attacker with knowledge of a valid username and associated SSH public key can obtain login access without needing the corresponding private key. This is a pre-authentication vulnerability affecting multiple IOS 15.x and IOS XE version families.

MitigationApply the appropriate Cisco IOS/IOS XE software updates referenced in the advisory. If immediate patching is not possible, restrict SSH access to trusted management networks or consider disabling SSH and using out-of-band management methods as a temporary control.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
iOSOperating system
Affected:= 15.2\(1\)sy= 15.2\(1\)sy0a= 15.2\(2\)e= 15.2\(2\)e1= 15.2\(2\)e2= 15.2\(2\)ea1= 15.2\(2a\)e1= 15.2\(2a\)e2= 15.2\(3\)e= 15.2\(3\)ea= 15.2\(3a\)e= 15.3\(3\)m1
Ios XeOperating system
Affected:= 3.6e.0= 3.6e.0a= 3.6e.0b= 3.6e.1= 3.6e.2= 3.6e.2a= 3.7e.0= 3.10s.0= 3.10s.0a= 3.10s.01= 3.10s.1= 3.10s.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
M
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:M/Au:N/C:C/I:C/A:C

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the IOS or IOS XE version
    Run 'show version' on the device and locate the version string in the output (typically the first line showing 'Cisco IOS Software' or 'Cisco IOS XE Software')
    Affected if The version matches one of the affected versions: 15.2(1)sy, 15.2(1)sy0a, 15.2(2)e, 15.2(2)e1, 15.2(2)e2, 15.2(2)ea1, 15.2(2a)e1, 15.2(2a)e2, 15.2(3)e, 15.2(3)ea, 15.2(3a)e, 15.3(3)m1 for IOS; or 3.6e.0, 3.6e.0a, 3.6e.0b, 3.6e.1, 3.6e.2, 3.6e.2a, 3.7e.0, 3.10s.0, 3.10s.0a, 3.10s.01, 3.10s.1, 3.10s.2
  2. Confirm SSH server is enabled
    Run 'show ip ssh' or 'show ssh' to verify the SSH server is active
    Affected if SSH server is enabled (this is required for the vulnerability to be exploitable)
  3. Verify RSA public key authentication is configured
    Run 'show crypto key mypubkey rsa' to check for configured RSA keys, and run 'show running-config | include ip ssh' to check for 'ip ssh pubkey-auth' configuration
    Affected if RSA authentication is enabled (the vulnerability specifically allows bypassing RSA public key authentication, so this configuration must be present for the flaw to apply)

The device is affected if it runs one of the listed IOS or IOS XE versions AND has SSH server enabled AND has RSA public key authentication configured.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the appropriate Cisco IOS/IOS XE software updates referenced in the advisory. If immediate patching is not possible, restrict SSH access to trusted management networks or consider disabling SSH and using out-of-band management methods as a temporary control.

Recommended fix High confidence

Upgrade to IOS XE 3.6.3E or later (for 3.6E branch), or 3.7.1E/3.10.6S/3.11.4S/3.12.3S/3.13.3S/3.14.1S depending on your release train

  1. 1. Identify the current Cisco IOS or IOS XE version using 'show version' command
  2. 2. Confirm affected version falls within the vulnerable range (iOS 15.2.x before fixed releases, or IOS XE 3.6E.x before 3.6.3E, 3.7E.x before 3.7.1E, 3.10S.x before 3.10.6S, 3.11S.x before 3.11.4S, 3.12S.x before 3.12.3S, 3.13S.x before 3.13.3S, 3.14S.x before 3.14.1S)
  3. 3. Download the appropriate fixed IOS/IOS XE release from Cisco's software download center
  4. 4. Back up the current device configuration using 'copy running-config startup-config' or 'write memory'
  5. 5. Upgrade the device firmware using 'archive download-sw' for IOS or the appropriate method for your platform
  6. 6. Reload the device after upgrade completes
  7. 7. Verify the new version is installed using 'show version'
  8. 8. Test SSH login functionality to confirm normal operation
Caveat Review Cisco release notes for your specific version upgrade to check for any command or feature changes; some older SSH key configurations may need re-importation after upgrade

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in iOS Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2015-6280 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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